How do I seperate these two "windows"?
So as You could see on the image above, the "lined" corners are crucial for window operations. Every window has TWO of them, so look for the top right and bottom left corners as circled green on the picture.

1) Drag that corner to the edge of the window to collapse the one next to it (bottom circle on the image)

2) Drag that corner from the edge to make a new one (top circle on the image)

As You could see I created new BIG windows in the center instead of that small on the right which seems that You want to achieve.

Hope it helps buddy, Sincerely, JayM